Brake shoe support mechanism



'Oct. 16, 1951 M. P..BI OMBERG BRAKE SHOE SUPPORT MECHANISM 2 Sheets-Sheet 1 Filed May 24, 1946 Oct. 16, 1951 M. P. BLOMBERG 2,571,410

BRAKE SHOE SUPPORT MECHANISM Filed May 24, 1945 2 Sheets-Sheet 2 97 q n a a; mvn fi l 3 1 g 27/ .21 if? pk a9 29 5;? f I W W Z s (297 a 6/ gf/ 7 X27 7 X69 Z69 59/ 919 Z97 Q97. Q9 3 atented ct. i, 1951 BRAKE SHOE SUPPORT MECHANISIK Martin P. Blomberg, Hinsdale, 111., assignor to General Motors Corporation, Detroit, Mich., a

corporation of Delaware Application May 24, 1946, Serial No. 672,093

9 Claims.

1 This invention relates to brake rig in for railwayvvehicles and more particularly to improved balancing means for brake heads supporting brake shoes. a

The principal object of the invention is to provide brake heads and automatically adjustable balancing means therefor to insure concentric positioning of the brake heads and brake shoes with respect to the wheels irrespective of the wheel and shoe wear thereby insuring uniform wear and longer shoe and wheel life.

Other objects and advantages of my invention wii become apparent by reference to the following detailed description and accompanying drawings, illustrating one form of the invention associated with a clasp type braking arrangement for which it is particularly adapted.

Figure 1 of the drawings is a side elevation view of one end of a railway vehicle truck provided with clasp type brake rigging and including my improved brake head balancing means therefor.

Figure 2 is an enlarged fragmentary side elevation view showing details of the invention.

Figure 3 is a sectional view taken on line 3-3 of Figure 2.

Figures 4 to 8 are views similar to Figure 3 showing modifications of the invention. Figure 1 of the drawings the character reference N indicates a portion of the side frame of a multiaxle truck, the axles I: of which, having wheels l secured thereon, are rotatably mounted in journal boxes ll movably guided in the side frame II in conventional manner The truck is provided with brake rigging of the clasp type including a pair of identical brake shoe'heads indicated generally at 2| for each truck wheel in which brake shoes 23 are keyed and automatic balancing or adjustin means for the heads to be subsequently described in detail.

As best illustrated in Figures 1 and 2 the brake head 2| to the right of the wheel IS, the balancing means and a brake actuating lever 23 therefor are mpunted for rotation on a bolt 21 supported at the ends in transversely aligned openings in the lower ends of hanger links 29--3| and said openings located slightly below the wheel center. The hanger links 293|"are pivoted for longitudinal swinging movement relative to the frame in the plane of the wheel on a pin 33 carried by the frame and extending through openings in the upper ends-of the hangers.

As best illustrated in Figures 2 and 3 one element of the automatic balancing means is a friction arm 33 having a small diameter hub end portion 31 shown on the bolt 21 and extending through openings in the lever and hanger 3|. A larger diameter hub portion 39 on the friction arm is shown extending through a bushing 4| in the outer web 43 of the head 2| and this hub portion 39 has a taperedexternal end surface 45 shown in engagement with a tapered internal surface of a counterbore 41 in the outer face of the lever 25. The inner hanger II has an lnwardh' extending hub portion 49 on which another bushing 4| in the other web 5| of the brake head 2| is rotatably mounted. The outer hanger 29 is also provided with an inwardly extending hub portion 53 shown extending into a counterbore 55 in the enlarged diameter hub portion 33 of the friction arm A compression spring 31 is placed in the space formed between the counterbore 55 in the hub portion 39 of the friction arm and a counterbore 59 in the inner end. of the hub portion 53 of the outer hanger 23. A nut 6| threaded on the outer end of the bolt 21 engages the outer face of the outerhanger 23 and draws the head 63 of the bolt against the inner face of the hanger 3| to cause compression of the spring 51 between the hanger 29 and the hub portion-.39 of the friction arm 33 thereby causing the tapered surface of the hub of the around a boss 61 of the friction arm 33 and extends to a boss is on a lug 1| on the web for the brake head 2|. The other web 3| of the brake head 2| is provided with a similar boss on em I3. The brake head 2| is also provided with, 8. lug 15 extending transversely across one end thereof and having openings in either end. As shown in Figure 2 an adjusting screw I1 is placed in the opening in the lug II on the outside'of.

the truck and is threaded in an opening in-the end of the friction arm 3 l and a lock nut I! on the screw engages the end of the arm and-countercloekwise movement or adjustment of. the brake head 2| relative to the friction arm 33 by the force exerted therebetween by the spring '3 causes contact between thelug I! of the 2| with the head of the adjusting screw 11 to limit counterclockwise movement of the head relative to the arm. The upper end of the brake actuating lever 23 is connected by a link 8| to the piston of the air brake cylinder, not shown. 'lhc'lower 3 end of the lever 2! is connected by a pin 03 shown inslots intheendsofstraddlebars ll having a slack adjuster. indicated generally at 81 associated therewith for adjusting the pin it relative to the slots 04. The other ends of the straddlebersllareconnectedtothelowerendofamother brake lever II by a pin Ii and the upper end of the lever II is pivoted for lon itudinal swinging movement to the left and in the plane of the wheel Ii on a pin .8 carried in an upper bracket ofthetruckframe ii.

Another assembly comprising a brake head 2 I, friction erm II, springs l|ll. adjusting screw I'l end lock nut is is shown mounted directly on the lever ll intermediate the ends and slightly below the wheel center on another bolt 21'. Pisures 4 to 6 illustrate various modifications of the mounting of the assembly directly on the lever II. For instance in the modification shown in Figure 8 the smaller diameter hub portion ll of the friction arm 8| is shown on the bolt 21' and extends through a bushing ii in the lever It and into a collar I! on which the bushing 4| in the web ll of the brake head is rotatably mounted. The bushing ll in the other web 43 of the brake heed II is rotatably mounted on the enlarged diameter hub portion 80 of the friction arm 85' end the tapered external surface ll thereon is shown in contact with an internally tapered surface of a counterbore II in the lever ll. The spring '1 is placed in the space formed by the counter-bore ll in the friction arm hub portion 80 end acep III on the outer end of the bolt 21. It will be evident that when the nut ti on the bolt is drawn up the nut willengage the cap Ill and drew the heed of the bolt into engagement with the collar-ll to compress the spring I! thereby holding the tapered surface II on the hub of the friction lever ll in frictional contact with the tapered counterbore I. of the lever II. It will be evident from the above that both the friction arms 3-3 are thus held in frictional engagement with the respective brake levers Ii-ll located on opposite sides of the wheel II and the end of each of the friction arms lt-ll' face toward the fulcrum ends of the levers formed by the pins "-li. The spring ll between the downwardly facing friction arm 3i and the head II to the right of the wheel ll tends to move the head counterclockwise relative to the lever it an amount determined by contact of the lug II on this head with the head of the adjusting screw ll threaded in the friction arm and the spring 65 between the upwardly facing friction arm 35' and the head II on the left side of the wheel likewisetendstourgethisheadinthesamedirection. counterclockwise relative to the lever 89 until the head lug It contacts the head of the a justing bolt 11.

With the brake shoes 28 supported in the heads ii on either side of the wheel II in concentric relation therewith by action of the springs II between the levers 28-" and friction arms 3H6 which are frictionally engaged with the respective levers 2H0. to retain the head lugs in contact with the head of the adjusting screws 11 in the friction arms the operation is as follows upon application of the brake shoes 28 to opposite sides of the wheel ll.

Movement of the upper end of the lever counterclockwise by the piston of the air brake cylinder causes the friction arm; head and shoe to the right of the wheel to move in the same direction counterclockwise about the pin It serving as the fulcrum and causes slight movement of the straddle bars ll to the right thereby causln theotherbrakeleveriltobeelso movedina counterclockwise direction about the pin ll serving as a fulcrum. As the friction arms Il-ll are frictionally engaged with the levers "-0! and the springs 0| urge the brake heads 2| counterclockwise relative to the levers and retain the brake head lugs II in contact with the heads of the adjusting bolts 11 in the friction arms the upper end of the brake shoe 2! to the right of the wheel and the lower end of the shoe II to the left of the wheel will contact the wheel first causing the shoes 28, heads II and lugs II thereon to move clockwise relative to the levers 25- and adjusting screws II on the friction arms 3H! and compress the springs 8| to permit concentric engagement of the shoes on opposite sides of the wheel, Release of the brakes is caused by movement of the levers 25-" clockwise about the fulcrum points "-88 and counterclockwise movement of the heads and shoes relative thereto is caused by action of the springs I between the heads Ii and friction arms IHI' frictionally engaged on the levers so that the head lugs II are again moved into contact with the heads of the adjusting bolts in the friction arms ll-Jlf to again position the show II in concentric release relation with respect to the wheel. As wear of the shoes Ii and wheel II progresses increased counterclockwise movement of the levers IMO is required to cause concentric engagement of the shoes with the wheel-and when the wear reaches a certain point the head lugs ll engage and move the ends of the friction arms Il-Jl' clockwise with respect to the levers 28-" to a new position upon engagement of the shoes with the wheel by slippage between the frictionally engaged tepered surfaces on the friction arms and levers. Upon subsequent disengagement or release of the shoes II, the springs 6! between the friction erms 3-85 in their new position on the levers "-0! will cause corresponding clockwise movement of the head II and shoes 28 relativeto theermstoa new corresponding position by contact between the head lugs It and heads of the adjusting screws 11. Adjustment of the friction arms relative to the levers taking place on successive brake applications of the brakes on account of wear and corresponding adjustment of the heads and shoes taking place upon subsequent release of the brakes serves to automatically position the heads and shoes in concentric relation of the wheels as wear of the shoes and wheels progresses. The above operation of the brake head balancing means insures proper automatic balancing or adjustment of the friction arms upon application followed by automatic adjustment of the heads and upon release of the brakes insures uniform wear of the shoes and this results in longer life of the shoes and wheels. As the heads ii are provided with lugs II on each web and a lug ll extending across one end adjacent thereto and provided with openings at either end for adjusting bolt 11 and the friction arms 35-35 may be positioned on the outside of the truck, the heads and arms may be used on any wheel of the truck and may be supported on the hangers 20-4! and brake actuating lever ll or supported on levers it in the manner described and all adjustments of the adjusting screws ll, located on the outside of the truck may accordingly be conveniently made.

It will be evident that the brake head Ii may be used with any convenient arrangement of brake levers, hangers and friction arms, each friction arm likewise being provided with a boss 21 by which a spring 55 may be located between this boss and a boss 69 on one side of the brake head. Each friction arm is also provided with means by which an adjusting screw 11 and lock nut 19 may be adjustably secured and locked to the friction arm to cooperate with a lug on one side of the brake head in the same manner as described with reference to these elements shown in Figures 1, 2 and 3. In Figures 4, 5, 6, 9 and 9 each of the friction arms is also provided with similar means for this cooperation and with similar means for urging the friction arm into frictional engagement with brake lever means to provide operation identical to that described with the structures shown in Figures 1, 2, 3 and 6.

The modification shown in Figure 4 differs from that shown in Figure 6 described above by the placing of a spring 29! directly between the nut 9i on a bolt 299 and a counterbore 295 in the hub 291 of a friction arm 299 and providing a collar 2 with an inwardly extending hub portion 2l9 so that the bushing 95 rests on the hub portions N3 and fit of the collar and friction arm. The spring serves in the same manner to retain the tapered surfaces of the friction arm and lever in engagement.

The modification in Figure 5 differs from that shown in Figure 4 by providing a collar 2 l1 having a large diameter portion 2l9 with a tapered surface 22! adapted to contact the tapered counterbore 99 of the lever 99 and a. smaller diameter portion 229 and a friction arm 225 having a large diameter hub portion 221 and a smaller diameter portion 229. The bushings H in the head webs 83-5! being supported on the large diameter portions 2l1-221 of the collar and arm and the bushing 95 of the lever 99 being supported on the smaller diameter portions 223 and 229 thereof. The bolt 203 and nut 6| compresses the spring 29l and holds the tapered surfaces of the collar and lever in frictional contact and also frictionally connects the friction arm 225 with both the lever 89 and collar 2 l1.

The modification shown in Figure '1 comprises two levers 211-219, a hanger 29l and a friction arm 28!. The bushings H in the webs 43-5! of the brake head 2| are supported on the hub portions 285-281 of the levers 211-219. The hub portion 291 of the lever 219 has a tapered end 289 in engagement with a tapered counterbore 29! of the friction arm 283 having a hub portion 293 supported in an opening in the hanger 28l. The spring 269 between the nut 6| on the bolt 2 and a counterbore 295 in the lever 219 holds the tapered surfaces of the arm and lever in frictional engagement and also holds the inner end face of the other lever hub portion 295 in frictional engagement with one face of the friction arm.

The modification in Figure 8 comprises two levers 211-219 identical to that shown in Figure 8 with the head 2| supported on the lever hub portions 295-481 and a friction arm 291 therebetween having a tapered counterbore 299 in engagement with the tapered end surface 299 of the lever 219. The spring 269 between the nut II on the bolt 2" holds the tapered surfaces of the friction arm 291 and lever 219 and one face of the friction arm and hub portion 285 of the other lever 211 in frictional engagement.

In all of the modifications of the invention shown in Figures 4 to 9 the friction arms are held in frictional engagement with a brake lever and serve in the same manner to automatically position a brake head and shoe in concentric relation with the wheel as the shoe and wheel wears.

From the above description of the various modiflcations of the invention the brake heads and shoes are adjusted concentrically with respect to the wheels when the brakes are released by the adjusting screws 11 and automatically adjusted to this position after application of the brakes followed by release, by action of the automatic brake head balancing means as wear of the shoes and wheels progresses.

I claim:

1. In a brake rigging for a vehicle wheel the combination of a brake lever angularly movable in the plane of the wheel, said lever having a bore extending therethrough parallel to the wheel axis and provided with a tapered counterbore at one end, a brake head having an arcuate face, opposite side projections adjacent one end, and aligned side bearing openings intermediate the ends, a brake shoe on the arcuate face of said brake head, annular support members in each side bearing opening of said head, one support member having a tapered end face engageable with the tapered counterbore and at least one support member having an arm extending radially outwardly from the outer end of a bearing opening of said brake head, said arm having spaced abutments thereon engageable with a side projection of said head, a bolt extending through the annular support members and the bore in said lever, said bolt having a head engageable with one support member and a nut threaded on the other end, a spring on said bolt compressed by said nut into engagement with the other support member to frictionally engage the tapered end of one support in the tapered counterbore of said lever, a second compression spring between said arm and a side projection of said head retaining a head projection in engagement with one abutment of said arm to retain said shoe in spaced concentric relation with respectto said wheel, the other abutment of said arm being engaged by a head projection upon excessive movement of said lever to apply the shoe to the wheel and to cause movement of said arm relative to said lever against the action exerted by both of said springs.

2. In a brake rigging for a vehicle wheel the combination of a brake lever angularly movable in the plane of the wheel, said lever having a bore extending therethrough parallel to the wheel axis and provided with a tapered counterbore in one end, a brake head having an arcuate face, side webs extending radially therefrom and having opposite side projections adjacent one end and enlarged diameter aligned side bearings intermediate the ends, a brake shoe on the arcuate face of said brake head, an annular support member in each side bearing of said head, one of said support members having a smaller diameter annular portion piloted in the bore of said lever and a tapered thrust face engageable with the tapered counterbore of said lever, at least one of said support members having an arm at the outer end provided with spaced abutments engageable with a head projection, a bolt extending through both support members and the bore in said lever and provided with a head engageable with one support member and a nut threaded on the other end, a spring on the bolt compressed between said nut and the other support member to cause frictional engagement of the tapered thrust face of one support member with the tapered counterbore of said lever and to cause frictional engagement of the other support member with the opposite side of said lever, a second compression spring between said arm and a head projection, to hold another head projection in engagement with an arm abutment and thereby retain said shoe in spaced concentric relation with the wheel, the other arm abutment being engaged and moved relative to said lever by a head projection against the actionexerted by both said springs upon excessive movement of said lever necessary to cause concentric engagement of said shoe to the wheel.

3. In a brake rigging for a vehicle wheel the combination of a brake lever angularly movable in the plane of a wheel, said lever having a bore extending therethrough parallel to the wheel axis and provided with a tapered counterbore in one end, a brake head having an arcuate face, side webs extending transversely therefrom having opposite side projectionsadjacent one end and centrally located bushed openings, an annular support member in each bushed opening of said head, one support member having a tapered inner end face engageable with the tapered counterbore of said lever, a brake shoe on the arcuate face of said head, a bolt extending through the annular support members and the lever bore and provided with a head engageable with one support member and a nut threaded on the other end. a spring on the bolt compressed between the nut and one support member to continuously urge the tapered inner .end face of one support member in frictional engagement with thetapered counterbore of the lever andto urge the inner end face of the other support member into frictional engagement with the opposite face of the lever, one of said support members having an armon the outer end, said arm having an abutment engageable with a head projection and another abutment adjustably secured to said first abutment and also cooperating with the same head projection, a second compression spring be-1 tween said arm and a head projection urging the first mentioned head projection into contact with the adjustable arm abutment to retain the shoe in spaced concentric relation with the wheel. the other arm abutment being engaged and moved by the first mentioned head projection relative to said lever against the combined forceof both said springs upon excessive angular movement of the lever necessary to cause concentric frictional engagement of said shoe with the wheel.

4. In a brake rigging for a vehicle wheel the combination of a brake lever angularly movable in the plane of the wheel; said lever having a bore extending therethrough parallel to the wheel axis and provided with a tapered counterbore in the outer end, a bushing in the lever bore, a brake head having an arcuate face, spaced side webs extending outwardly therefrom and pro- 4 port members having a head engageable with the inner support member and a nut threaded on the outer-end, a third annular support member on said bolt adjacent the nut and rotatable in the outer annular support member, a spring on said bolt between said third and said outer support members urging the tapered thrust surface of said outer support member into frictional mgagement with the tapered counterbore of mid lever. a second bolt extending through an opening in an-outer projection of said head and threaded to said arm, a second spring between said arm and a second outer projection of said head for urging said nrst projection into ongagement with the head of said second bolt to hold said shoe in spaced concentric relation with the wheel, said first head projection engaging said arm and moving it relative to said lever against the combined action of both said springs upon excessive movement of said lever to cause concentric engagement of said shoe with the wheel.

5. Ida brake rigging for a vehicle wheel the combination of a brake lever angularly movable in the plane of the wheel. said lever having a bore extending therethrough parallel to the wheel axis and provided with a tapered counterbore in the outer end, a bushing in the bore of said lever, a brake head having an arcuate face. side webs extending outwardly therefrom having opposlte side projections adjacent one end and centrally located bushed openings therein. a brake shoe on the arcuate face of said brake head. inner andouter annular-support members. each rotatable in one of the hushed openings of said head. each support member having a smaller diameter annular portion extending into the hubing in said lever bore, the outer'support member having a tapered thrust face engageable in the tapered counterbore of said lever and having an with the inner support member and a nut threaded on the outer end, a spring on said bolt compressed between said nut for continuously urging the tapered thrust face of said outer support member into frictional engagement with the counterbore of said lever and also urging the inner end of said inner support member 'into frictional-engagement with the opposite side of said lever, said arm being contactable with a vided with opposite side projections and 'centrally located axially aligned bushed openings, a

shoe removably secured to the face of said head, an outer annular support memmr rotatably supporting the outer bushed opening of the head and provided with an arm on the outer end and a tapered thrust face engageable with the tapered counterbore of the lever and also provided with a smaller diameter annular support extending through and rotatable in the bushing in the bore of said lever, an inner annular support member rotatably supporting the other bushed opening of said head and supported on the smaller' diameter annular portion of the outer support projection on the outer web of said head, a second bolt threaded to said arm having a head also contactable with said projection. a second spring between-said arm and another web projection urging said first mentioned projection into contact with the head of said second bolt to normally retain said shoe in spaced concentric relation with the wheel. said first projection engaging and moving said arm relative to said lever against the force exerted by both said springs upon excessive movement of said lever necessary to cause concentric engagement of said shoe with the .webs extending outwardly therefrom and provided with opposite side projections adjacent one end and centrally located openings. a bushing in each web opening, inner and outer support members of annular form in each bushing of said head, each of said support members having a smaller diameter inner end portion extending into the bushing in the lever opening, said outer support member having a tapered thrust face engageable with the tapered counterbore of said lever, said inner support membe having an arm on the outer end, a bolt extending through the support members and the lever opening and having a head engageable with the inner member and a nut threaded on the outer end, a spring on said bolt compressed between said outer member and said nut for continuously urging the thrust surface of said outer member into frictional engagement with the lever counterbore, said arm of the inner member being contactable with a projection of the inside web of the head, an abutment adjustably secured to said arm and also contactable with said projection, a second spring between another inside web projection and said arm urging said first mentioned web projection into contact with the adjustable abutment of said arm to hold said shoe in spaced concentric relation with the wheel, said first projection engaging and moving'said arm relative to said lever against the combined force of both said springs upon excessive movement of said lever necessary to cause concentric engagement of said shoe with the wheel.

7. In a brake rigging for a vehicle wheel the combination of brake linkage means supported for angular movement in the plane of the wheel, a brake head having an arcuate face, opposite side projections adjacent one end and a bearin opening intermediate the ends, a brake shoe carried on the arcuate face of the brake head engageable with the wheel, bearing means carried by the brake linkage means and located in and rotatably supporting the bearing opening of the brake head about an axis parallel to the wheel axis, said brake linkage means having a tapered annular friction surface concentric with the bearing means carried thereby, a friction arm having a tapered annular frictional surface engageable with tapered annular frictional surface of said brake linkage meanaand spaced abutments engageable by a side projection of said brake head,

8. In a brake rigging for a vehicle wheel the g combination of a pair of spaced brake levers movabl in the plane of the wheel and having annular hub portions, one of said hub portions having an inwardly extending annular tapered surface, a

brake head having an arcuate face, opposite side projections adjacent one end and aligned bearing openings intermediate the ends rotatably supported on said lever hub portions about an axis parallel to the vehicle wheel, a brake shoe supported on the arcuate face of the brake head, a friction arm located between the annular hub portions of said levers and having an annular hub portion provided with an annular tapered friction surface engageable with the tapered annular surface of said lever hub portion, and spaced abutments on said arm engageable with a side projection of said head, supporting means pivotally supporting th annular hub portion of said friction arm, clamping means extending through the annular hub portions of said levers and said friction arm, spring means on said clamping means urging the tapered annular surfaces of said friction arm and said lever hub portion into frictional engagement and additional spring means urging a side projection of said head into engagement with one of the abutments of said friction arm.

9. In a brake rigging for a vehicle wheel the combination of a pair of spaced brake levers movable in the plane of the wheel and having annular hub portions, one of said hub portions having an inwardly extending tapered annular .surface, a brake head having an arcuate face, opposite side projections adjacent one end and opposite side bearings rotatably supported on the annular hub portions of said levers about an axis parallel to the axis of the vehicle wheel, a brake shoe supported on the arcuate face of the brake head, a friction arm having an annular hub portion provided with a tapered annular surface engageable with the tapered annular surface of said lever hub portion and having spaced abutments engageable with a side projection of said brake head, clamping means extending through the annular hub portions of said brake levers and said friction arm, spring means on said clamping means urging the tapered annular surfaces of said friction arm and said lever hub portion into frictional engagement and additional spring means urging a side projection of said brake head into engagement with one abutment of said friction arm. MARTIN P. BLOMBERG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1 1,686,648 Baselt Oct. 9. 1928 2,079,554 Hedgcoek May 4, 1937 2,394,382 Holin Feb. 5, 1946 

